2 Answers
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At ESRI 3.0 the dojo version behind the ESRI framework was upgraded to 1.7. Dojo 1.7 has a fundamental change to the way in which modules are loaded called AMD. See this help topic for advice on migrating to AMD and the 3.0 release notes. You look should at these topics in order to understand what changed between the two versions

When I created a fiddle for your previous question I initially created it using version 3, but as you specifically requested the code in 2.8 I changed it. Here is the one I created using ESRI version 3.2 (and therefore dojo version 1.7), notice the differences in how the modules are required (no more dojo.require). Whilst there is some backwards compatibility, it is highly recommeneded you move to the new model as at dojo 2.0 backwards compatibility will not be supported (i.e anywhere you use dojo.)